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Coombs Indirect Test

Published: July 27, 2026Updated: August 25, 2026

The Coombs Indirect Test measures the presence of antibodies in the blood that could target and destroy red blood cells, often associated with hemolytic anemia or transfusion reactions.

Quick summary

The Coombs Indirect Test detects antibodies that may cause red blood cell destruction.

Medically reviewed by WellAlly Editorial TeamLast reviewed August 25, 2026Editorial policy

Key facts at a glance

Units
result
Clinical utility
diagnostic
Result kind
qualitative
FDA-cleared
Bio-Rad Coombs Indirect, Ortho Clinical Diagnostics Coombs
interpretation: {"text":"Indicates the presence of antibodies that may cause hemolytic reactions, requiring careful blood product selection and monitoring.","label":"Positive"}; {"text":"Suggests no detectable antibodies, reducing the risk of hemolytic reactions but not eliminating the possibility of other complications.","label":"Negative"}

The Coombs Indirect Test, also known as the indirect antiglobulin test (IAT), is designed to identify antibodies in the patient's serum that could potentially attack foreign red blood cells. This is particularly important in pre-transfusion testing and during pregnancy to prevent hemolytic reactions.

The test involves mixing the patient's serum with reagent red blood cells and then adding an antiglobulin reagent. If antibodies are present, they will cause the red blood cells to clump together, indicating a positive result.

A positive Coombs Indirect Test suggests the presence of antibodies that could cause hemolysis, which is crucial for managing blood transfusions and preventing complications in newborns due to maternal antibodies.

Frequently asked questions

What does a positive Coombs Indirect Test mean?
A positive result indicates the presence of antibodies that could cause hemolysis, necessitating further evaluation and precautions during blood transfusions or in newborns.
Is the Coombs Indirect Test used for diagnosing autoimmune diseases?
While it can detect antibodies, the test is more commonly used to assess the risk of hemolytic reactions rather than diagnosing autoimmune conditions.
  1. 1
    American Association for Clinical Chemistry (AACC)Source
  2. 2
    Mayo ClinicSource

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This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 25, 2026. · Read our editorial policy